Coating and processing apparatus and method

ABSTRACT

There is provided a coating and processing apparatus including a spin chuck horizontally holding a quadrangular substrate and rotating the substrate in a horizontal plane, a coating solution nozzle for supplying a coating solution to a front surface of the substrate horizontally held by the spin chuck, and a solvent supply mechanism provided in the spin chuck for supplying a solvent to a back surface of the substrate, in which the solvent supplied to the back surface of the substrate is allowed to reach the back surface and side surface of each of corners of the substrate by centrifugal force, thereby removing the coating solution attached.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/795,269, filed on Mar. 9, 2004, and is based upon and claims thebenefit of priority from prior Japanese Patent Application No.2003-063851, filed Mar. 10, 2003. The entire contents of each of theabove-listed applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coating and processing apparatus forapplying a coating solution and removing the coating solutionundesirably attached on the back and side surfaces of a mask substrateto be subjected to a light exposure step of a photolithographic processfor a semiconductor device, and a method of coating and removing thecoating solution.

2. Description of the Related Art

In manufacturing a semiconductor device and a liquid crystal display(LCD) device, a predetermined pattern is photolithographically formed ona photoresist film on a substrate by use of a mask substrate (reticle),that is, a so-called photolithographic process is performed. Thepredetermined pattern of the mask substrate is formed by forming aresist coating film on one of the surfaces of the mask substrate by spincoating and exposing the resist coating film to light to develop it.

Japanese Patent Application KOKAI No. 2000-271524 describes a coatingapparatus for forming a resist coating film by applying a resistsolution on a quadrangular substrate by spin coating. The coatingapparatus has a spin chuck having a rectangular recess in the uppersurface. When the quadrangular substrate is placed in the rectangularrecess, the upper surface of the substrate is flush with that of thespin-chuck. While the quadrangular substrate placed in the recess isrotated by a spin-chuck, a resist solution is supplied to the uppersurface of the substrate. After the supply of the resist solution isstopped, the substrate is still continued to rotate to cause airflowfrom the center of the substrate to the periphery along the surface ofthe substrate. Using the airflow, a solvent is vaporized from the resistsolution. This is called “spin-dry”. As a result, a desired resistcoating film is formed.

When the dimensional accuracy of a mask pattern is low, the accuracy ofwiring width is significantly affected in all semiconductor wafersexposed to light with the pattern as a mask. Therefore, it is necessaryto prevent particle attachment to the mask substrate as much aspossible. The probability of attaching particles to the mask substrateis the greatest when the substrate is transferred immediately after acoating process. When a transfer arm member transfers a mask substrate,it is desirable to prevent the transfer arm member from being in contactwith the mask substrate as much as possible. Actually, as shown in FIG.8A, the regions 11 with which the transfer arm member can be in contactare limited only to four corners and the middles of four sides of thesubstrate G. Since the transfer arm member is prohibited from being intouch with a back surface 13 b and a side surface 13 e of the masksubstrate, the support piece 52 of the transfer arm member is allowed incontact only with a chamfered C plane 13 c, as shown in FIG. 8C.

However, when a resist solution is applied to a mask substrate by use ofa conventional apparatus, the resist solution enters the recess,attaches to the side surface and back surface of the mask substrate andthe attached resist solution is transferred to a transfer arm member,causing cross contamination. The cross contamination frequently occursparticularly at the corner portions of the substrate.

When the resist solution is supplied to a spin-rotating substrate G, itis radially dispersed along the surface (upper surface) 13 a of thesubstrate G and shaken off from the substrate G by centrifugal force.However, as shown in FIG. 1, when a resist solution 100 reaches theperiphery of the substrate G from the center of the substrate 13 a, partof the resist solution changes its direction for the corners of thesubstrate, entering a clearance between the side surface 13 e and theinner peripheral surface of the recess of the spin chuck. Further, theresist solution may possibly reach the back surface 13 b of thesubstrate G. The corners of the substrate G are supported by supportpieces 52 of the transfer arm member, the resist solution 100 istransferred from the substrate G to the support pieces 52, and furthertransferred from the support pieces 52 to another substrate G, causingcross contamination. Besides this, the resist solution thus transferredis dried into particles, which may deposit on another substrate G.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a coating andprocessing apparatus and method for coating a coating solution andremoving an unnecessary coating solution deposited on the side and backsurfaces of a quadrangular substrate.

According to the present invention, there is provided a coating andprocessing apparatus comprising:

a spin chuck horizontally holding a quadrangular substrate and rotatingthe substrate in a horizontal plane;

a coating solution nozzle for supplying a coating solution to a frontsurface of the substrate horizontally held by the spin chuck; and

a rinse liquid supply unit provided in the spin chuck for supplying arinse liquid to a back surface of the substrate,

in which the rinse liquid supplied to the back surface of the substrateis allowed to reach the back surface and side surface of each of thecorner portions of the substrate by centrifugal force produced byrotation of the spin chuck, thereby removing the coating solutionattached.

According to the present invention, since a quadrangular substrate, spinchuck and rinse liquid supply unit are synchronously rotated, thecentrifugal force on and surface tension of the rinse liquid work inconcert, with the result that the resist deposit can be efficientlyremoved from the back and side surfaces of the corner portions of asubstrate. Therefore, when the corner portions of the substrate are heldby a transfer arm member, the resist solution cannot be transferred tothe transfer arm member. In this manner, cross contamination via thetransfer arm member can be effectively prevented.

The rinse liquid supply unit has a rinse liquid supply port at theportion corresponding to each of the corner portions of the substrate.

The spin chuck has a holding plate facing the back surface of thesubstrate and substrate-supporting members for supporting the peripheraledge of the substrate with a clearance between the substrate and thesubstrate holding plate.

Furthermore, the rinse liquid supply unit has a plurality of nozzles forspraying a rinse liquid onto the lower surface of a rotating holdingplate and guide channels for guiding the rinse liquid to the clearancebetween the back surface of the substrate and the holding plate with thehelp of centrifugal force.

The guide channels are through-holes radially arranged on a concentriccircle around a rotation center of the holding plate.

Furthermore, the guide channels are through-holes obliquely passingoutward from the lower surface to the upper surface of the holding platefor smoothly supplying the rinse liquid applied to the lower surface ofthe holding plate by the nozzle, toward the back surface of thesubstrate.

Each of the guide channels serving as a rinse liquid supply port isformed at a position of the holding plate corresponding to each of thecorner portions of the substrate.

The guide channels are formed near the corresponding corner portions ofthe substrate so as to bridge the diagonal lines of the substrate.

A cover having a rinse liquid collecting unit is provided on the backsurface side of the holding plate; and the rinse liquid in the rinseliquid collecting unit is supplied onto the back surface through theguide channel.

A wall is further provided along the periphery of the holding plateexcept around the corner portions of the substrate so as to face theside surfaces of the substrate.

Cut-away portions are formed such that the corner portions of thesubstrate held by the spin chuck are exposed; and the substrate istransferred while being held by the transfer arm member at the backsurfaces of the exposed corner portions.

Spacers are provided on the inner surfaces so as to face each other withthe diagonal line interposed between them for aligning the substrateheld by the spin chuck and directing the rinse liquid toward theextension of the diagonal line of the substrate.

According to the present invention, there is provided a method ofcoating a coating solution on a quadrangular substrate and removing acoating solution undesirably attached onto a back surface and sidesurface of the quadrangular substrate, comprising the steps of:

(a) holding the quadrangular substrate horizontally by a spin chuck;

(b) supplying a coating solution from a coating solution nozzle to asurface of the substrate held by the spin chuck and spreading thecoating solution with the help of centrifugal force by rotating the spinchuck around a vertical axis; and

(c) supplying a rinse liquid to a back surface of the substrate from arinse liquid supply unit while rotating the spin chuck and the rinseliquid supply unit synchronously around the vertical axis, therebypermitting the rinse liquid to reach the corner portions of thesubstrate with the help of centrifugal force to wash away the coatingsolution.

In step a, the periphery of the substrate is held by the substratesupporting member provided on the holding plate with a clearance betweenthe substrate and the holding plate; and in step c, the rinse liquid issupplied to the clearance.

In step c, the rinse liquid is supplied through a guide channel servingas a rinse liquid supply port formed at a position of the holding platecorresponding to each of the corner portions of the substrate.

The guide channels are through-holes radially arranged on a concentriccircle around a rotation center of the holding plate. Further, the guidechannels are through-holes obliquely passing outward from the lowersurface to the upper surface of the holding plate for smoothly directingthe rinse liquid sprayed on the lower surface of the holding plate bythe nozzle toward the back surface of the substrate.

In step c, the substrate is rotated by the spin chuck alternately at apredetermined low rotation speed and high rotation speed within a rangeof 200 to 1,500 rpm.

In step c, an acceleration rate for changing the low rotation speed tothe high rotation speed and a deceleration rate for changing the highrotation speed to the low rotation speed fall within the range of 1,000to 5,000 rpm/second.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic perspective view showing the surface state of asubstrate when a resist is coated by a conventional apparatus;

FIG. 2 is a schematic sectional view showing a coating and processingapparatus according to an embodiment of the present invention, alongwith a block diagram showing peripheral elements;

FIG. 3 is perspective view, partly broken away, showing a spin chuckaccording to an embodiment;

FIG. 4A is a plan view of a spin chuck as viewed from the above;

FIG. 4B is an enlarged plan view showing part of a spin check, as viewedfrom the above;

FIG. 5 is a plan view showing a spin chuck according to anotherembodiment, as viewed from the above;

FIG. 6 is a plan view showing a spin chuck according to anotherembodiment, as viewed from the bottom;

FIG. 7 is a plan view showing a spin chuck according to a gist portionof a transfer arm for transferring a quadrangular substrate to a spinchuck;

FIG. 8A is a schematic plan view of a quadrangular substrate;

FIG. 8B is a partial sectional view of a quadrangular substrate;

FIG. 8C is an enlarged side view showing a part of a quadrangularsubstrate supported by a transfer arm;

FIG. 8D is an enlarged plan view showing a part of a quadrangularsubstrate supported by a transfer arm;

FIGS. 9A to 9D are sectional views showing the steps of cleaning theback surface of a substrate by a coating and processing method accordingto an embodiment of the present invention;

FIG. 10 is a timing chart of a back surface cleaning step of a coatingand processing method according to an embodiment of the presentinvention;

FIG. 11 is a schematic perspective view showing the state where thecorner portions of the back surface of a substrate are cleaned with arinse liquid;

FIG. 12A is a plan view showing a spin chuck according to anotherembodiment;

FIG. 12B is a partial plan view showing a spin chuck according toanother embodiment;

FIG. 13 is a perspective view of a spin chuck according to anotherembodiment, partially broken away;

FIG. 14 is a perspective view showing a spin chuck according to anotherembodiment;

FIG. 15 is an enlarged plan view showing a part of a rinse liquid supplyunit according to another embodiment;

FIG. 16 is an enlarged plan view showing a part of a rinse liquid supplyunit according to another embodiment;

FIG. 17 is an enlarged plan view showing a part of a rinse liquid supplyunit according to another embodiment;

FIG. 18 is an enlarged plane view showing a part of a spin chuckaccording to another embodiment;

FIG. 19 is a schematic plan view showing the entire coating anddeveloping apparatus; and

FIG. 20 is a schematic perspective view showing the entire coating anddeveloping apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Preferable embodiments of the present invention will be explained withreference to the accompanying drawings.

As shown in FIG. 2, a spin chuck 2 is accommodated within a cup 3 of thecoating and processing apparatus. The spin chuck 2 receives a masksubstrate G (work piece) from a transfer arm mechanism 5 shown in FIG. 7and performs predetermined coating treatment to the substrate G. Themask substrate G (work piece) is formed of square quartz glass having aside length L1 of 152±0.4 mm, on which a chromium oxide (Cr₂O₃) coatingfilm is applied, and further on the chromium oxide, a resist coatingfilm formed. The thickness of the mask substrate G is a quarter inch(6.35±0.1 mm) and the projected length of the C plane is 0.2 to 0.6 mm.

The spin chuck 2 has a holding plate 23 for holding a quadrangularsubstrate G. The holding plate 23 is connected to a driving unit 22 viaa rotation axis 21. The driving unit 22, which is controlled by acontroller 60, rotates the spin chuck 2 around the Z-axis and moves thespin chuck up and down along the Z-axis.

Next, the rinse liquid supply unit will be explained.

The rinse liquid supply unit is provided below the spin chuck 2 forcleaning the back and side surfaces of the substrate G. The rinse liquidsupply unit includes a rinse liquid supply source 64, a plurality ofnozzles, a cover, a guide channel provided on a holding plate 23. Aplurality of nozzles 41 communicates with the rinse liquid supply source64 and supported by a circular plate 32 such that each of the nozzlesfaces the lower surface of the holding plate 23. The nozzles 41 areattached to the circular plate 32. These nozzles are divided into twogroups, which are arranged axisymmetric with respect to a shaft 21 andobliquely arranged so as to face each other.

The cover 40 has a clean bowl form with a large hole at the bottom, asshown in FIG. 3, and attached to the lower portion of the holding plate23 so as to cover entire lower surface of the holding plate 23. Theupper portion of the cover 40 is completely opened and the lower portionthereof has a central hole 40 b. A rinse liquid collecting portion 40 a,which is formed at the lower portion extending from the peripheral tothe inside, defines a central opening 40 b. The rinse liquid dischargedfrom the nozzles 41 passes through the central opening 40 b of the cover40, strikes the lower surface of the holding plate 23, heads for theguide channel 43 along the lower surface of the holding plate 23 bycentrifugal force, passes through the guide channel 43 and reaches thelower surface of the substrate G.

Furthermore, an arch-shape guide channel 43 passing through the holdingplate 23 is provided near a corner of the substrate G, morespecifically, 20 mm inside the corner. More specifically, the rinseliquid discharged from the nozzles 41 is supplied to a clearance betweenthe surface of the cover 40 and the back surface of the holding plate23, passed through the rinse liquid collecting section 40 a and suppliedtoward the back surface of the substrate G from the guide channel 43.

The guide channels 43 are arranged so as to clean spacers 27 at the timethe back surface of the substrate G is cleaned. More specifically, theguide channels 43 are provided so as to span the region surrounded bylines connecting the center of the substrate G and spacers 27. By virtueof this arrangement, the guide channel 43 acquires a function ofregulating the flow of a rinse liquid toward the corner portions of thesubstrate G, as described later.

In this embodiment, the guide channels are arranged near the cornerportions so as to span the diagonal lines of the substrate. However, theguide channels may be arranged out of the diagonal lines as long as therinse liquid reaches to the corner portion of the substrate.

Furthermore, on the surface of the holding plate 23 a protrusion 44 isprovided, for example, near the middle of each of the individual sidesof the substrate G. The protrusions 44 serve as substrate supportingmembers for supporting the back surface of the substrate G whileslightly separating upward from the surface of the holding plate 23 inorder to prevent particles from attaching to the back surface of thesubstrate G. More specifically, the clearance is formed between thesubstrate G and the holding plate 23 by slightly lifting the substratefrom the surface of the holding plate 23. A rinse liquid supplied fromthe guide channel 43 flows through the clearance to clean the cornerportions of the substrate.

The protrusions 44 and the spacers 27, more specifically, portions ofthem in contact with the substrate G, are coated with polyether etherketone (PEEK) to protect the substrate G from damage. The PEEK maycontain carbon fibers. The other portion of the spin chuck may beappropriately formed of aluminium, an aluminum alloy, stainless steelcoated with fluorine, polyether ether ketone (PEEK), or a combination ofthese.

As shown in FIG. 2, a first guide ring 31 is provided so as to surroundthe side periphery of the spin chuck 2. The first guide ring 31 has anupper surface virtually flash with that of the spin chuck 2. The lowersurface of the first guide ring 31 slopes down and outward (the innerlower surface is higher than the outer lower surface). At the lower sideof the spin chuck 2, the circular plate 32 is arranged so as to surroundthe rotation shaft of the spin chuck 2. Further, a second guide ring 33(having an angle-form section) is formed so as to surround the outerperiphery of the circular plate 32. The second guide ring 32 has thesame outer radius as the first guide ring 31, and the outer peripheraledge bends and extends below.

An outer cup 3 is provided so as to surround guide rings 31 and 33. Theouter cup 3 has an opening portion larger than the spin chuck 2 at thetop so as to allow the spin chuck 2 to move up and down. Between theside peripheral surface and the outer peripheral surfaces of the firstand second guide rings, a clearance serving as an air channel 34 isformed.

In the bottom portion of the outer cup 3, there is a curved and bendchannel formed with the help of the outer-periphery of the second guidering 33. The curved and bend portion serves as an air/liquid separationportion. An excessive coating liquid passes through an outer chamber 35and is discharged from a drainage port 36, whereas a gas passes throughan inner chamber 37 a and is expelled from an exhaust port 37 by thesuction force of a pump (not shown). Note that the exhaust amount of thecup according to the present invention is, for example, 900 inch aqua(corresponding to 260 to 270 Pa), which corresponds to about 5 to 6times that of a general silicon wafer coating apparatus. Therefore, in acoating and processing apparatus of the present invention, since the cuphas a larger exhaust amount than a silicon wafer coating apparatus, itis possible to prevent particles from attaching to the substrate G evenif a small amount of particles are present in the cup.

Furthermore, on the upper surface, a ring plate 38 is provided which hasan inner diameter, for example, 100 to 160 mm, which is smaller than thediameter of the opening portion of the outer cup 3, and an outerdiameter larger than the opening portion of the outer cup 3. The ringplate 38 is supported movably up and down by a driving mechanism (notshown). Moreover, a nozzle 39 is provided so as to face the uppersurface of the mask substrate G and held by the spin chuck 2. The nozzle39 communicates with a resist supply source 63 by way of a pipe. Theresist supply source 63 has a built-in mass flow controller (MFC) forcontrolling the supply amount of a resist solution. The operation of theMFC is controlled by a controller 60. The nozzle 39 is supported movablyup and down within a X-Y plane by a plurality of moving mechanisms (notshown).

Referring now to FIGS. 3, 4A and 4B, the spin chuck 2 will be explainedin detail.

The holding plate 23 of the spin chuck 2 for holding a substrate G is asquare slightly larger than the substrate. The holding plate 23 haswalls 24 which are formed along the sides of the square except thecorner portions. A recess portion is formed of the holding plate 23 andthe walls 24. When a substrate G is placed in the recess, the holdingplate 23 faces the back surface of the substrate G. Furthermore, at thecorner portions, there are cut-away portions 25 are formed by cuttingaway part of the holding plate 23 in a square form. Therefore, when asubstrate G is placed on the holding plate 23, each of the cornerportions of the substrate G (for example, about 3 to 7 mm) is exposed tothe outside from the holding plate 23. A transfer arm mechanism 5 holdsthe exposed portions when the substrate G is loaded and unloaded.

On the upper edge of each of the walls 24, an airflow controlling member26 (flat plate) is formed. The airflow controlling member 26 is a flatplane horizontally provided so as to be flush with the surface of thesubstrate G. As viewed from the top, the periphery of theairflow-controlling member 26 is formed in an arch form. Morespecifically, the flat-plate airflow controlling member 26 is arrangedalong the side of the substrate G with a gap between them so as to benearly flush with the surface of the substrate G. The airflowcontrolling member 26 is, for example, formed at a position by 0.5 mmlower than the level of the substrate G and is not formed at the cornerportion of the substrate G.

In the proximity of each corner portion of the spin chuck 2, a pair ofspacers 27 are arranged and respectively attached to the walls 24,thereby producing a clearance, for example, about 1.5 mm, between thesubstrate G on the holding plate 23 and the wall 24. The spacer isformed into a shape such as a triagonal pyramid or cylinder, by whichthe spacer is brought into point or line contact with the side peripheryof the substrate G. The spacer also has an alignment function forholding a substrate G at a desired position on the spin chuck 2. Sincethe substrate G is defined (fixed) by four pairs of spacers 27 form theperiphery, it does not wobble on the spin chuck 2 when the substrate Gis rotated.

Next, a spin chuck 2A according to another embodiment will be explained.

FIG. 5 is a plan view of the spin chuck 2A as viewed from the uppersurface side and FIG. 6 is a plan view of the spin chuck 2A as viewedfrom the back surface side. The spin chuck 2A has substantially a squarecover 23A on the back surface. The peripheral flange 23 f of the cover23A is fixed by a screw on the periphery of the opening of an airflowcontrolling member 26A. Since the opening of the airflow controllingmember 26A is square and the corner portions of the substantially squarecover 23A are partially cut away, airflow ports 25 are formed at theportions corresponding to the corner portions of the substrate G in aplan view. The size and shape of the airflow ports 25 are determined bythe sizes of the opening of the airflow controlling member 26 andcut-away portions at the four corners of the cover 23A. In thisembodiment, the shape of the airflow port 25 is a fan of 5 to 10 mmradius. On the peripheral portion of the airflow controlling member 26A,a plurality of spacers 27A and protrusions are positioned to prevent thesubstrate G from wobbling on the spin chuck 2A.

The cover 23A has 72 liquid supply ports 43 radially and concentricallyarranged. More specifically, these liquid supply ports have the sameshape and size and are arranged at regular pitches. A shown in FIG. 9B,when a rinse liquid R is discharged from the nozzle 41 toward the cover23A, the back surface of the substrate G is cleaned with the rinseliquid R as shown in FIG. 9C. Since the liquid supply ports 43 areradially arranged, the rinse liquid R is supplied in every direction tosufficiently clean the entire back surface of the substrate G.

Next, the transfer arm mechanism 5 and the mask substrate G will beexplained with reference to FIGS. 7, 8A to 8D.

The transfer arm mechanism 5 has a horizontal arm member 51 driven by anXYZθ driving mechanism (not shown) for transferring a mask substrate Gbetween the spin chuck and the transfer arm mechanism 5. The horizontalarm member 51 has a circular (arcuate) arm main body with an open tip,and four support pieces 52, as shown in FIG. 7. The four support pieces52 each project inward from the inner peripheral surface of the arcuatearm body and hold the C plane 13 c of the corner portion of the masksubstrate G.

To prevent contamination of the mask substrate G with particles, othermembers must not be in contact with the back surface 13 b and sidesurface 13 e. The regions 11 with which other members may be in contactare positioned only at the corners and the middle portions of foursides. In addition, the support pieces 52 of an arm member each are incontact with the mask substrate G only at the C plane 13 c, as shown inFIG. 8C and not in contact with the back surface 13 b and side surface13 e of the substrate G. More specifically, the support piece 52 has ataper guide surface 52 a, a tip stopper portion. 52 b, and a bendingportion 52 c. When the mask substrate G is transferred to the transferarm mechanism 5, it slides along the taper guide surface 52 a whilebeing in contact with the support piece 52 only at the C plane 13 c, andstops when the C plane 13 c reaches the bent portion 52 c. Since theinner diameter of an imaginary circle connecting the tip stopperportions 52 b is smaller than the outer diameter of the mask substrateG, the mask substrate G may not fall off from the support pieces 52. Asviewed from the top, as shown in FIG. 8D, the support piece 52 has apair of bent portions 52 c. A corner of the mask substrate G is incontact with the pair of bent portions 52 c.

As shown in FIG. 8B, the mask substrate G has a chromium oxide (Cr₂O₃)coating film 12 b on a transparent substrate 12 a of quartz glass, and aresist coating film 12 c is formed on the coating film. The chromiumoxide coating film 12 b has an average thickness of 30 to 60 nm and theresist coating film 12 c has an average thickness of 400 to 500 nm.

The mask substrate G has a side length L1 of 152±0.4 mm and a thicknessof a quarter inch (6.35±0.1 mm). The projected length of the C-plane 13c is 0.2 to 0.6 mm.

The case where a mask substrate G is transferred from the transfer armmechanism 5 to the spin chuck 2 will be briefly explained. First, thetransfer arm mechanism 5 holding the substrate G is moved above the spinchuck 23. Then, the arm member 51 is moved down while passing thesupport pieces 52 through the airflow port 25. In this manner, theregion (substrate) surrounded by the arm member 51 is moved relative tothe spin chuck 2, thereby mounting the substrate G on the holding plate23. When the substrate G is unloaded from the spin chuck 2, theaforementioned operation is reversely performed.

Next, a method of forming a coating film on the surface of the substrateG by using the coating and processing apparatus mentioned above will beexplained.

First, the spin chuck 2 is moved up to above the outer cup 3 in thestate where the ring plate 38 is set at the predetermined uppermostposition and a substrate G is transferred to the spin chuck 2 from atransfer arm mechanism 5. Then, the spin chuck 2 moves down whileholding the substrate G and further the ring plate 38 moves down to thepredetermined lowermost position. Subsequently, the coating solutionnozzle 39 is guided to a position facing the center of the substrate G.Thereafter, a coating solution, a resist solution, is discharged towardthe center portion of the substrate G from the coating solution nozzle39 and the substrate G is subsequently rotated at a high speed togetherwith the spin chuck 2 synchronously for 2 to 3 seconds at a firstrotation speed, for example, 2,500 rpm. The resist solution supplied tothe substrate G spreads toward the peripheral edge of the substrate G bycentrifugal force given by rotation of the substrate G and finally anexcessive resist solution is shaken off from the substrate.Subsequently, while the coating solution nozzle 39 is moved back, thesubstrate G is rotated together with the spin chuck 2 at a secondrotation speed as low as, e.g., 1000 rpm, for 15 to 30 seconds, therebyaccelerating evaporation of a solvent (thinner) contained in a resistsolution on the surface of the substrate G. As a result, a resist filmhaving a thickness of about 0.6 μm is formed of the remaining resistcomponents on the surface of the substrate G. Incidentally, a resistsolution may be supplied from the coating solution nozzle 39 while thespin chuck 2 is rotated.

Next, a step of rinsing the back surface of the substrate G (referred toas a “back rinse step”) will be explained with reference to FIGS. 9A to9D, 10 and 11.

To the side surface and back surface of the substrate coated with theresist solution, resist components 200 are deposited as shown by hatchedlines in FIG. 9A. To clean the resist components, a rinse liquid R isdischarged from the rinse liquid discharge nozzles 41 while thesubstrate G is rotated at, for example, 500 rpm. More specifically, therinse liquid R is sprayed from the nozzles arranged in a zigzag fashionsuch that the spray flows cross each other toward an inside positionfrom the cover 40 attached to the back surface of the holding plate 23at a flow rate of 60 ml/min. Since centrifugal force is working, therinse liquid R is also guided along the back surface of the holdingplate 23 and supplied to a clearance between the cover 40 and theholding plate 23. The rinse liquid R may be directly supplied to theclearance between the cover 40 and the holding plate 23.

The rinse liquid R is directed to a rinse liquid collecting portion 40 aby centrifugal force (centripetal force), passed through the guidechannel 43, introduced into a clearance between the substrate G and theholding plate 23, radially spread around the center of rotation bycentrifugal action and diffused.

As a result, as shown in FIG. 11, two flows of rinse liquid R areformed: one is directed toward the corner portion and the other isdirected toward the wall 24. The latter flow strikes the surface of thewall 24 and changes direction. However, since the spacer 27 prevents theflow from spreading to the inside, the flow is finally directed towardthe corner portion of the substrate G. As explained, the rinse liquid Rsupplied from each of the liquid supply ports 43 flows toward thecorresponding corner portion of the back surface of the substrate G andis then diffused.

As shown in FIG. 9C, the rinse liquid R that has reached the peripheryof the airflow port 25 further goes outward while attaching to the backsurface side of the substrate G by the function of surface tension. Therinse liquid R that has expanded outward over the periphery of thecorner portion of the substrate G flows while partly going to the sidesurface of the substrate. When the rinse liquid R that has reached thecorner of the corner portion of the substrate G is shaken off, it goesto the side surface due to the surface tension. Consequently, a risingcorner 300 can be cleaned.

Incidentally, the boundary between the back surface 13 b and the sidesurface 13 e of the substrate G and that between the surface 13 a andthe side surface 13 e are rounded to form the C planes 13 c, as shown inFIG. 8C. The rinse liquid R flows along the back surface 13 b and thenalong the C plane 13 c and goes to the side surface 13 e to clean thesurface 13 e.

After 5 to 30 seconds from initiation of supply of the rinse liquid R,the supply of the rinse liquid R is stopped and the spin chick isrotated for several seconds to shake off the rinse liquid R. Aftercompletion of cleaning, the ring plate 38 is moved up and then the spinchuck 2 is lifted, and the transfer arm mechanism 5 receives thesubstrate by the substrate support pieces 52 and unloads it, as shown inFIG. 9D.

An embodiment of the back rinse step will be explained with reference toFIG. 10.

After transfer of a mask substrate G to the spin chuck 2 is completed,rotation of the spin chuck 2 is first started at a low speed of 200 rpmat time-point 1 (t1). At time-point 2 (t2), the speed is increased to1,500 rpm at an acceleration rate of 1,000 to 5,000 rpm/second andmaintained at 1,500 rpm for 3 seconds (t3 to t4). During this period, arinse liquid is sprayed to the holding plate 23 from the nozzles 41. Attime point, t4, the rotation speed is reduced to 200 rpm at adeceleration rate of 1,000 to 5,000 rpm/second and maintained at 200 rpmfor 3 seconds (t5 to t6). During this period, the rinse liquid iscontinuously sprayed from the nozzles 41. At time point t6, the rotationspeed is increased to 1,500 rpm at an acceleration rate of 1000 to 5000rpm/second and maintained at 1,500 rpm for 3 seconds (t7 to t8). Duringthis period, the rinse liquid is continuously sprayed from the nozzles41. At time point t8, the rotation speed is reduced to 200 rpm at adeceleration rate of 1000 to 5000 rpm/second and maintained at 200 rpmfor 3 seconds (t9 to t10). During this period, the rinse liquid iscontinuously sprayed from the nozzles 41. At time point t10, therotation speed is increased to 1,500 rpm at an acceleration rate of 1000to 5000 rpm/second and maintained at 1,500 rpm for 3 seconds (t11 tot12). During this period, the rinse liquid is continuously sprayed fromthe nozzles 41. At time point t12, supply of the rinse liquid from thenozzles 41 is stopped and the rotation speed is decreased at adeceleration rate of 1000 to 5000 rpm/second. In this way, the rotationof the spin chuck 2 is terminated. The high-speed rotation and thelow-speed rotation of the spin chuck are alternately repeated 3 times.In this manner, the resist deposit is successfully removed completelyfrom the back surface 13 b and the side surface 13 e of the masksubstrate G. Specifically, the resist deposit can be satisfactorilyremoved from the C-plane 13 c of the mask substrate G by alternatelychanging the low-speed rotation and the high-speed rotation of the spinchuck 2.

When the rotation speed during the low-speed rotation operation is lowerthan 200 rpm (e.g., 100 rpm), resist goes from the upper surface to thelower surface. Since such a disadvantage is produced, the lowermostvalue of the rotation speed of the substrate is set at 200 rpm duringthe back rinse step. On the other hand, when the rotation speed duringthe high-speed rotation operation exceeds 1,500 rpm, the rinse liquidtends to be rejected by the holding plate 23. As a result, the rinseliquid is splashed back toward the nozzles 41 and scattered on theperiphery of the spin chuck. For this reason, the upper value of therotation speed of the substrate during the back rinse step is set at1,500 rpm.

According to the embodiment mentioned above, a rinse liquid is suppliedto a clearance between the substrate G and the holding plate 23, whilethe substrate G and the holding plate 23 are synchronously rotated. Byvirtue of this constitution, centrifugal force produced by rotation andthe surface tension of the rinse liquid supplied on the substrate Gcooperationally work to clean the back surface and side surface of thecorner portion of the substrate G. Consequently, the resist solutionattached at least to the side surface near the bottom and the backsurface of the corner portion during resist-coating time can be removed.Therefore, even if the back surface of the corner portion is held by thetransfer arm mechanism 5, the substrate support pieces 52 of thetransfer arm mechanism 5 can be prevented from contamination. As aresult, even if the substrates G are loaded into and unloaded from theapparatus one by one by the transfer arm mechanism 5, the corner portionof substrates G cannot be contaminated. Furthermore, when the substrateG is transferred without being held at four corners by the transfer armmechanism 5, for example, in the case where another unit holds thesubstrate G at the four corners, so-called cross contamination can beprevented.

Furthermore, according to the embodiments mentioned above, the guidechannel 43 is arranged at a position corresponding to each of the cornerportions of the substrate G, specifically, at a position from which arinse liquid is supplied, the rinse liquid can reach the corners of thesubstrate, for example, on the diagonal lines of the substrate G. Withthis arrangement, the rinse liquid can be aggressively (positively)supplied toward a target to be cleaned, that is, the corner portions ofthe substrate G. Furthermore, since the rinse liquid collecting portion40 a is provided, the rinse liquid can be collected in the guide channel43 by the help of centrifugal force (centripetal force) compared to thecase where the rinse liquid is supplied from the center of the substrateG, and the amount of the rinse liquid can be reduced. As a result, thepresent invention can advantageously decrease the cost.

Furthermore, by providing the wall 24 along the periphery of thesubstrate G, a rinse liquid is supplied toward the corner portions as amatter of course without caring. In addition, since a guide channel 43is formed so as to span the lines connecting the center of the substrateG and a pair of spacers 27, the spacers 27 can be cleaned. In addition,since the rinse liquid strikes the wall 24 and flows in the clearancebetween the substrate G and the wall 24, it is regulated by the spacers27 so as not to expand inward. As a result, the rinse liquid can besupplied toward the corner portions without fail.

According to the embodiment, the cut-away portions 25 are formed in thespin chuck 2 and the substrate G is transferred to and from the transferarm mechanism by holding the corner portions of the substrate G exposedin the cut-away portions 25.

Therefore, load and unload of the substrate G can be easily performed.

The cover 40 of the present invention is not limited to the structurehaving a rinse liquid collection portion 40 a (it may partly extend).For example, as shown in FIGS. 12A and 12B, the cover 40 may be in theform of a trough like a ring covering and including the guide channels43. Even if the cover has a ring-form, the rinse liquid discharged fromthe rinse liquid discharge nozzles 41 toward the back surface of theholding plate 23 flows along the back surface of the holding plate 23 bycentrifugal force, and reaches the trough, splashes out of the guidechannel 43 and is supplied to the substrate G. Therefore, the sameeffects can be obtained as mentioned above.

Furthermore, the structure of the spin chuck of the present invention isnot limited to that having the walls 24 on the spin chuck 2. Thestructure of the spin chuck shown in FIG. 13 may be used. Morespecifically, the spin chuck has the guide channels 43, cut-awayportions 25, the holding plate 23 for placing a substrate G thereon atthe center, and spacers 28 provided in the periphery of the substrateholding region and air-flow controlling members 26. The outer edge ofthe airflow-controlling member 26 exhibits the same shape as that of theholding plate 23. Each of the airflow controlling members 26 issupported by the spacer at the inner periphery. Also in this case, therinse liquid supplied from the guide channel 43 into a clearance betweenthe substrate G and the holding plate 23 is directed toward the cornerportions of the substrate due to centrifugal force generated by thesynchronous rotation of the substrate G and the holding plate 23.Therefore, the corner potions can be cleaned. Thus, the same effects asmentioned above can be obtained.

Furthermore, in the present invention, the structure of the spin chuck 2is not limited to that having the cut-away portions 25. The structureshown in FIG. 14 may be used. More specifically, there is a spin chuckhaving a guide channel 43, a circular holding plate 23 having asubstrate holding region at the center an airflow controlling member 26having an opening region corresponding to the substrate holding region,and a spacer 28 supporting the member 26. Also in this case, a rinseliquid can go to the side surface of the substrate G due to the surfacetension. Therefore, the same effects as mentioned above can be obtained.However, in this case, the corner portions of the substrate G are notexposed to the outside from the holding plate 23. In order for thetransfer arm mechanism 5 to hold the substrate G, for example,through-holes are formed in the surface of the holding plate 23 and asubstrate lift-up member passing though each of the through-holes isprovided. The substrate G is lifted up by the substrate lift-up membersmoved through the holes and transferred to the transfer arm mechanism 5.

In the present invention, as shown in FIG. 15, liquid flow guide members6 may be provided on the surface of the holding plate 23 in order tocontrol the direction of flow of the rinse liquid. Even with thisstructure, the same effects as above can be obtained.

The arrangement of the liquid-flow guide members 6 may be desirablydetermined depending upon the purpose, more specifically, whether arinse liquid is directed toward the corner portions or not without failor a rinse liquid is directed so as to clean the spacer 27 without fail.

Furthermore, in the present invention, the shape of the guide channel 43is not limited to a fan. Circular-form guide channel may be arrangedside by side, as shown in FIG. 16. How to arrange the guide channels 43is desirably determined by performing a preliminary test.

In the present invention, the guide channels 43 need not necessaryformed in the surface of the holding plate 23 and may be formed in theinner side surface of the wall 24. Also in this case, the same effectsas mentioned above can be obtained by supplying a rinse liquid to aclearance between the substrate G and the holding plate 23. Furthermore,a guide channel 43 may be provided so as to directly supply a rinseliquid to the side surface of each of the corner portions of thesubstrate G.

In the present invention, the cut-away potions 25 need not be alwaysformed in a rectangular shape and may be formed in an arch form. Tosupply a rinse liquid to the corners of the substrate G without fail,the substrate holding portion may extend into the cut-away portion, asshown in FIG. 18 and further may be slightly inclined upward even withthe structure, the same effects as mentioned above can be obtained.

Furthermore, in the present invention, the substrate G is not limited toa mask substrate and may be a glass substrate for a liquid crystaldisplay and also a semiconductor wafer. In the present invention, thecoating process is not limited to a process for coating a resistsolution and may be a developing process performed by supplying adeveloper to a substrate after light exposure or a cleaning processperformed by supplying a rinse liquid to a substrate.

Finally, a coating and developing apparatus having a coating andprocessing apparatus of the present invention as a coating unit U1 willbe explained with reference of FIGS. 19 and 20.

In the figure, a carrier block B1 has a carrier-mounting section 71 formounting a carrier 70, which stores a plurality of substrates G, and atransfer means 72. At the back of the carrier block B1, a process blockB2 is connected thereto. In the process block B2, the transfer armmechanism 5 mentioned above is provided as a main transfer mean. So asto surround the transfer arm mechanism 5, the coating unit U1 and adeveloping unit U2 for developing a substrate G after light exposure arearranged at the right hand side, and a cleaning unit U3 for cleaning asubstrate G at the left hand side as viewed from the carrier block B1.Furthermore, shelves U4 and US, in which heating/cooling units forheating and cooling a substrate and transferring units for transferringa substrate are stacked in multiple stages, are arranged in the frontand the back sides respectively. Furthermore, the transfer arm mechanism5 is configured so as to move up and down, back and forth, and rotatearound the vertical shaft, thereby enabling transfer of a substrate G toand from the coating unit U1, developing unit U2, cleaning unit U3 andstack units U4 and U5. Moreover, the process block B2 is connected to alight-exposure block B4 via an interface block B3. In the light-exposureblock B3, a substrate G coated with a resist film is exposed to light byusing a predetermined mask. In the interface block B3, a transfer means73 is provided which is configured so as to transfer a substrate Gbetween a transfer unit, one of the units stacked in the stack unit U5,and the light-exposure block B4.

The flow of a substrate G will now be briefly explained. When thecarrier 70 storing substrates G is loaded into the carrier mountingsection 71 from the outside, a substrate G is taken out from a cassetteC by the transfer means 72 and transferred to the transfer arm mechanism5 via a transfer unit stored in the stack unit U4 and then loaded intothe cleaning unit U3, heating unit, cooling unit and coating unit U1,sequentially in this order. In this manner, for example, a resist filmis formed. Subsequently, the substrate is prebaked in the heating unitand cooled to a predetermined temperature in the cooling unit and,thereafter, loaded into the light-exposure block B4 by the transfermeans 73 and then exposed to light. After that, the substrate G isloaded into the heating unit, in which post exposure baking is performedat a predetermined temperature. The resultant substrate is cooled to apredetermined temperature in the cooling unit and then developed in thedeveloping unit U2. The substrate G to which predetermined treatmentshave been applied and on which, for example, a resist pattern is formedis returned to the carrier 70.

According to the present invention, a substrate and a rinse liquidsupply unit are synchronously rotated to supply a rinse liquid to theback surface of the substrate, thereby cleaning the side surfaces of thecorner portions and the back surface of the substrate. Hence, thesubstrate can be transferred while holding the four corners thereof.

1. A method of spin coating a coating solution on a quadrangular masksubstrate used in exposure processing of a photolithographic process andremoving a coating solution undesirably attached to a back surface and aside surface of the substrate by a rinse liquid, comprising the stepsof: (p1) preparing a spin chuck comprising a cover having a rinse liquidcollection portion, a coating solution nozzle, a rinse liquid nozzle, apair of spacers mounted on the spin chuck, a holding plate having a topsurface being provided with liquid flow guide members that control adirection of flow of the rinse liquid toward the corner portions, and aguide channel opening at a position corresponding to each of cornerportions of the substrate on the holding plate and communicating withthe rinse liquid collection portion; (a) supporting the back surface ofthe substrate by substrate supporting members while slightly separatingupward from the surface of the holding plate, and positioning thesubstrate to the spin chuck by the pair of spacers thereby holding thesubstrate horizontally with the holding plate provided on the spin chuckby a periphery of the substrate, with a clearance between the substrateand the holding plate; (b) supplying the coating solution from thecoating solution nozzle to a surface of the substrate held by the spinchuck and spreading the coating solution with the help of centrifugalforce by rotating the spin chuck around a vertical axis; and (c)supplying the rinse liquid to the clearance to reach the back surface ofthe substrate from the rinse liquid nozzle while rotating the holdingplate synchronously with a substrate around the vertical axis, andsupplying the rinse liquid through the rinse liquid collection portionand the guide channel serving as a rinse liquid supply port formed at aposition of the holding plate corresponding to each of the cornerportions of the substrate, thereby permitting the rinse liquid to reachthe corner portions of the substrate with the help of centrifugal forceto wash away the coating solution.
 2. The method according to claim 1,wherein the guide channels are through-holes radially arranged on aconcentric circle around a rotation center of the holding plate.
 3. Themethod according to claim 1, wherein the guide channels arethrough-holes obliquely passing outward from a lower surface of theholding plate to an upper surface of the holding plate for smoothlydirecting the rinse liquid sprayed on the lower surface of the holdingplate by the nozzles toward the back surface of the substrate.
 4. Themethod according to claim 1, wherein, in the step (c), the substrate isrotated by the spin chuck alternately at a predetermined low rotationspeed and high rotation speed with a range of 200 to 1,500 rpm.
 5. Themethod according to claim 4, wherein, in the step (c), an accelerationrate for changing the low rotation speed to the high rotation speed anda deceleration rate for changing the high rotation speed to the lowrotation speed fall within the range of 1,000 to 5,000 rpm/second. 6.The method according to claim 1, wherein the guide channels are anarch-shape.
 7. A method of spin coating a coating solution on aquadrangular mask substrate used in exposure processing of aphotolithographic process and removing a coating solution undesirablyattached to a back surface and a side surface of the substrate by arinse liquid, comprising the steps of: (p1) preparing a spin chuckcomprising a holding plate, a cover having a rinse liquid collectionportion, a coating solution nozzle, a rinse liquid nozzle, a pair ofspacers mounted on the spin chuck, air flow controlling members beingsupported by air flow controlling member spacers, an outer edge of theair flow controlling members being the same shape as the holding plate,and a guide channel opening at a position corresponding to each ofcorner portions of the substrate on the holding plate and communicatingwith the rinse liquid collection portion; (a) supporting the backsurface of the substrate by substrate supporting members while slightlyseparating upward from the surface of the holding plate, and positioningthe substrate to the spin chuck by the pair of spacers thereby holdingthe substrate horizontally with the holding plate provided on the spinchuck by a periphery of the substrate, with a clearance between thesubstrate and the holding plate; (b) supplying the coating solution fromthe coating solution nozzle to a surface of the substrate held by thespin chuck and spreading the coating solution with the help ofcentrifugal force by rotating the spin chuck around a vertical axis; and(c) supplying the rinse liquid to the clearance to reach the backsurface of the substrate from the rinse liquid nozzle while rotating theholding plate synchronously with a substrate around the vertical axis,and supplying the rinse liquid through the rinse liquid collectionportion and the guide channel serving as a rinse liquid supply portformed at a position of the holding plate corresponding to each of thecorner portions of the substrate, thereby permitting the rinse liquid toreach the corner portions of the substrate with the help of centrifugalforce to wash away the coating solution.
 8. The method according toclaim 7, wherein the guide channels are through-holes radially arrangedon a concentric circle around a rotation center of the holding plate. 9.The method according to claim 7, wherein the guide channels arethrough-holes obliquely passing outward from a lower surface of theholding plate to an upper surface of the holding plate for smoothlydirecting the rinse liquid sprayed on the lower surface of the holdingplate by the nozzles toward the back surface of the substrate.
 10. Themethod according to claim 7, wherein, in the step (c), the substrate isrotated by the spin chuck alternately at a predetermined low rotationspeed and high rotation speed with a range of 200 to 1,500 rpm.
 11. Themethod according to claim 10, wherein, in the step (c), an accelerationrate for changing the low rotation speed to the high rotation speed anda deceleration rate for changing the high rotation speed to the lowrotation speed fall within the range of 1,000 to 5,000 rpm/second. 12.The method according to claim 7, wherein the guide channels are anarch-shape.